1. Field of the Invention
The present invention relates to printing machines, and more particular, to silk screen printing machines capable of printing on a variety of geometric configurations.
2. Prior Art
Silk screening is of course an ancient art, but it has been modernized to significant extents as a result of automation or semi-automation of the equipment utilized to produce the silk screening designs. One of the major commercial applications today is in the printing of bottles and plastic containers of various geometric configurations and surfaces of revolution such as for example, cylindrical, oval and rectangular.
In some operations of printing such geometrically configured containers and the like, it is necessary to hold the silk screen stationary while moving the squeegee across the surface of the silk screen in order to pass the printing liquid through the screen and create the design. In still other applications it is necessary to reciprocate laterally the silk screen while maintaining the squeegee stationary in engagement with the surface of the screen in order to pass the printing liquid through the screen.
Since silk screen printing machinery is often utilized for a variety of applications it must generally be adaptable to either mode of operation. It is further worthy to note that there are other variations in the type of relative movement between the squeegee and the silk screen such as a rotary motion of the squeegee to cause the printing liquid to be passed through the screen as the squeegee moves in a circular pattern. Such a novel additional apparatus is disclosed for example in applicant's copending application and which is adapted to be attached to the machine of the present invention.
The present invention, however, is more closely related to those silk screen printing apparatus when used in such a manner that either the squeegee or the silk screen is reciprocated laterally. In such type of silk screening operations it is necessary that once the design has been transferred to the surface of the container, provision be made for separating the silk screen from the surface of the container so that the object can be removed and a subsequent object inserted for engagement with the silk screen to continue the operation on that object.
In this regard, it is important that both the squeegee and the screen be separated as closely perpendicular as possible from the object in order that the design which has been printed on the object is not smeared when the surface of the silk screen is removed from the object. In one well known prior art device, this is accomplished by a parallelogram linkage which is designed to rotate the silk screen carrier and the squeegee away from the object being printed on with the parallelogram linkage further causing relative movement between the squeegee and the silk screen.